What version of 389-ds-base is installed? There were bugs around csn location that were fixed in the very latest version of the LDAP server on RHEL 7.9. So make sure you are running the latest version of 389-ds-base.
As for replication being broken, you can confirm this by making a "dummy" change somewhere and checking if that change is present on the other replicas (give it some time to replicate of course, but it shouldn't take more than a few seconds).
As for re-initializing just make sure you are initing from the most current/accurate replica.